Allelic Frequency of DPYD Genetic Variants in Patients With Cancer in Spain: The PhotoDPYD Study

INTRODUCTION: Identifying polymorphisms in the dihydropyrimidine dehydrogenase (DPYD) gene is gaining importance to be able to predict fluoropyrimidine-associated toxicity. The aim of this project was to describe the frequency of the DPYD variants DPYD*2A (rs3918290); c.1679T>G (rs55886062); c.2846A>T (rs67376798) and c.1129-5923C>G (rs75017182; HapB3) in the Spanish oncological patients. MATERIAL AND METHODS: Cross-sectional and multicentric study (PhotoDPYD study) conducted in hospitals located in Spain designed to register the frequency of the most relevant DPYD genetic variants in oncological patients. All oncological patients with DPYD genotype were recruited in the participant hospitals. The measures determined where the presence or not of the 4 DPYD previously described variants. RESULTS: Blood samples from 8054 patients with cancer from 40 different hospitals were used to determine the prevalence of the 4 variants located in the DPYD gene. The frequency of carriers of one defective DPYD variant was 4.9%. The most frequently identified variant was c.1129-5923C>G (rs75017182) (HapB3), in 2.9%, followed by c.2846A>T (rs67376798) in 1.4%, c.1905 + 1G>A (rs3918290, DPYD*2A) in 0.7% and c.1679T>G (rs55886062) in 0.2% of the patients. Only 7 patients (0.08%) were carrying the c.1129-5923C>G (rs75017182) (HapB3) variant, 3 (0.04%) the c.1905 + 1G>A (rs3918290, DPYD*2A) and one (0.01%) the DPYD c.2846A>T (rs67376798, p.D949V) variant in homozygosis. Moreover, 0.07% were compound heterozygous patients, 3 carrying the DPYD variants DPYD*2A + c.2846A>T, 2 the DPYD c.1129-5923C>G + c.2846A>T and one the DPYD*2A + c.1129-5923C>G variants. CONCLUSIONS: Our results demonstrate the relatively high frequency of DPYD genetic variants in the Spanish patient with cancer population, which highlights the relevance of their determination before initiating a fluoropirimidine-containing regimen.